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arXiv 1710.03396physics.med-ph
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前列腺动态增强磁共振图像的分割

Segmentation of Dynamic Contrast-Enhanced Magnetic Resonance Images of the Prostate

Wuilian Torres, Leonardo Cordero, Miguel Martín-Landrove, Antonio Rueda-Toicen

摘要:

动态对比增强磁共振成像(DCE-MRI)是定位、表征和评价异常前列腺组织的有价值的工具。当患者接受顺磁性造影剂时,以规则的时间间隔生成MRI体积的超快梯度回波采集。结果是时间序列,其中每个体素表现出造影剂摄取(洗入)和后洗出的特定行为。在这项工作中,提出了一种分割方法,组在一起的相邻体素具有相似的对比度洗出的反应,使用的区域生长GrowCut元胞自动机算法的变体,迭代地根据一个细胞的关系,它的相邻细胞。最初,通过形态滤波器确定种子细胞,所述形态滤波器识别体积中的均质区域,所述均质区域代表前列腺中的临床相关类型的组织。每个细胞的特征在于三个参数:标识相关体素中组织类型的标签,具有DCE-MRI时间序列值的向量,以及值在0和1之间的强度系数,其表示细胞属于其分配标签的概率。每个非种子细胞都可以修改其状态;这发生在每个细胞受到其邻居的攻击时,攻击强度与细胞之间时间序列值的相似性成反比。如果被攻击的细胞的强度小于它的一个邻居的攻击强度,它的状态会改变为攻击细胞的状态。被攻击的细胞也会更新其强度,使其等于它被征服的攻击强度。为了对所得到的分割进行临床验证,我们使用了来自美国国家癌症研究所(NCI)癌症成像档案(TCIA)数据库的各种病例。

英文摘要:

Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) is a valuable tool to localize, characterize, and evaluate anomalous prostate tissue. Ultrafast gradient-echo acquisitions of MRI volumes are generated at regular time intervals while the patient receives a paramagnetic contrast agent. The result is a time series where each voxel exhibits a particular behavior of contrast uptake (wash-in) and posterior wash-out. In this work, a segmentation method is proposed that groups together neighboring voxels with similar contrast wash-out responses, using a variant of the region growing GrowCut cellular automaton algorithm, that evolves iteratively according to the relationship of a cell to its neighboring cells. Initially, seed cells are determined through morphological filters that identify homogeneous regions in the volume that are representatives of the clinically relevant types of tissues in the prostate. Each cell is characterized by three parameters: a label that identifies the type of tissue in the associated voxel, a vector with the values of the DCE-MRI time series, and a strength coefficient with values between 0 and 1 that represents the probability with which the cell belongs to its assigned label. Every non-seed cell can modify its state; this occurs when each cell is attacked by its neighbors with a strength of attack that is inversely proportional to the similarity of the values of the time series between the cells. If the strength of the attacked cell is less than the strength of the attack of one of its neighbors, its state changes to the one of the attacking cell. The attacked cell also updates its strength making it equal to the strength of the attack with which it was conquered. To perform a clinical validation of the resulting segmentations, we used various cases from the database of The Cancer Imaging Archive (TCIA), National Cancer Institute (NCI).

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